I'll assume with this answer that you're running CBC in Lighthouse Studio (otherwise the instructions are different).
In the analysis module, go to the Analysis Settings area and choose the Settings gear icon. Then select Attribute Coding from the menu. At the bottom of the next screen is an area in which you can add interactions. Click the Add button and identify the two attributes whose interaction you want to include. Then run the analysis. When you create the simulator using the resulting model, the interactions should be automatically included. Please call our Support department if you need help with the mechanics.